[Intel-gfx] [PATCH 2/4] iommu/vt-d: Disable superpage for Broxton igfx

Ville Syrjala
2021-07-09T16:48:07Z

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Broxton has known issues with VT-d superpage. Namely frame buffer
compression (FBC) can't be safely used when superpage is enabled.
Currently we're disabling FBC entirely when VT-d is active, but
I think just disabling superpage would be better since FBC can
save some power.

TODO: might be nice to disable superpage only for the igfx iommu
instead of both iommus
TODO: would be nice to use the macros from include/drm/i915_pciids.h,
but can't do that with DECLARE_PCI_FIXUP_HEADER()

Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: iommu@lists.linux-foundation.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
drivers/iommu/intel/iommu.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 4fff2c9c86af..40117f868761 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5623,6 +5623,13 @@ static void quirk_iommu_nosp(struct pci_dev *dev)
intel_iommu_superpage = 0;
}

+/* Broxton igfx has issues with superpage */
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0A84, quirk_iommu_nosp);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1A84, quirk_iommu_nosp);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x1A85, quirk_iommu_nosp);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x5A84, quirk_iommu_nosp);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x5A85, quirk_iommu_nosp);
+
/* Geminilake igfx appears to have issues with superpage */
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x3184, quirk_iommu_nosp);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x3185, quirk_iommu_nosp);
--
2.31.1